1. Field of the Invention
Ethylene glycol is the simplest and most important of the glycols which are widely used for many purposes and applications in industry. For example, ethylene glycol is a valuable component in antifreeze solutions for automobile engines, aircraft engines, ice-cream plants, and brewery cooling systems. Additionally, ethylene glycol finds widespread application in moistening and softening tobacco, cellophane, glue, gelatin, casein, paper and textile fibers, as well as solvents for dyes, printing inks, essential oils and various gums and resins. Similarly, ethylene glycol derivatives are important as emulsifying agents, plasticizers and explosives. Ethylene glycol was first synthesized by Wurtz in 1859, but, from a commercial standpoint, did not become important until 1925 when it was produced in large quantities via the of ethylene ofethylene oxide.
The iridium complex catalysts, as disclosed herein, exhibit superior hydrocarbon synthesis characteristics and selectivity to ethylene glycol formation when contacted with carbon monoxide and hydrogen under reaction conditions.
2. Description of the Prior Art
The reaction of carbon monoxide and hydrogen to produce monohydric and polyhydric alcohols is appreciated and disclosed by the prior art. Generally, however, most known processes produce a undesirably large mixture of alcohols, aldehydes, ethers, ketones and carboxylic acids, in addition to the polyhydric alcohol.
For example U.S. Pat. No. 3,833,634, entitled "Manufacture of Polyfunctional Compounds", issued to Pruett et al, on Sept. 3, 1974 describes a process for the preparation of polyfunctional oxygen-containing compounds, such as ethylene glycol and its derivatives, which comprise reacting carbon monoxide with hydrogen in the presence of a rhodium complex catalyst. In particular, tetrairidium dodecacarbonyl is described as unsuitable for use in the production of polyfunctional products such as ethylene glycol by the reaction between carbon monoxide and hydrogen at increased temperature and pressure.
Another process is set forth in U.S. Pat. No. 3,940,432, entitled "Process for Making Ethylene Glycol", issued to Walker et al, on February 4, 1976 which relates to the production of ethylene glycol and methanol from carbobn monoxide and hydrogen, wherein said carbon monoxide and hydrogen are reacted in the presence of a metal carbonyl catalyst at elevated pressures and temperatures. Particularly, carbon monoxide and hydrogen are contacted with rhodium carbonyl cluster ions which can be associated with a counterion which may be rhodium per se, hydrogen, ammonia or any monovalent or polyvalent metal such as sodium, potassium, etc., the rarer earth metals of Group VIII metals of the periodic table, for example, iridium.